Conventional pleated fabric window shades that stack the fabric when opened, typically have a head rail mounted at or above the top of the window from which the fabric depends, and a bottom rail attached along the lower edge of the fabric. The pleated shade is opened and closed by raising and lowering the bottom rail so that, in the open position, the fabric stacks against the head rail at the top of the window.
Pleated fabric window shades can also be constructed with an additional rail (top rail) that is attached along the upper edge of the fabric and suspended from the head rail. The top rail permits the shade to be opened and closed from the top as well as from the bottom, by lowering and raising the top rail so that in the open position, the fabric stacks against the bottom rail at the bottom of the window. This type of shade allows selective covering of the upper part, the lower part, or the entire window, and is commonly referred to as top-down-bottom-up (TDBU) shade because it can be lowered and raised from the top or from the bottom.
Unfortunately, conventional TDBU shades are expensive because they usually employ two complex and costly independent lift systems, one to operate and hold the bottom rail and one to operate and hold the top rail. Although some TDBU shades employ single lift systems, such shades are still relatively expensive because of the complexity and cost of the lift system.
For that and other reasons, there remains a need for an inexpensive TDBU shade.